Charles Darwin & the Theory of Evolution
Charles Darwin & the Theory of Evolution
In the mid-1800’s, a British naturalist by the name of Charles
Darwin developed a theory of how evolution works. A naturalist is a
person who studies plants and animals by observing them. Recall
that a theory is an explanation of the natural world that is well
supported by evidence. During his voyage around the world on the
HMS Beagle, Darwin observed many plants and animals.
Darwin was especially interested in the organisms he saw on
the Galapagos Islands off the coast of South America. He noticed that
each island had a slightly different environment. The giant tortoises
looked different on each island. They had different shaped shells
which determined whether they could eat high vegetation, low
vegetation, or both. Like the tortoises, different types of
mockingbirds and finches lived in different island environments. Each
one had a different type of beak that determined the type of food
that they could eat.
In the mid-1800’s, a British naturalist by the name of Charles
Darwin developed a theory of how evolution works. A naturalist is a
person who studies plants and animals by observing them. Recall
that a theory is an explanation of the natural world that is well
supported by evidence. During his voyage around the world on the
HMS Beagle, Darwin observed many plants and animals.
Darwin was especially interested in the organisms he saw on
the Galapagos Islands off the coast of South America. He noticed that
each island had a slightly different environment. The giant tortoises
looked different on each island. They had different shaped shells
which determined whether they could eat high vegetation, low
vegetation, or both. Like the tortoises, different types of
mockingbirds and finches lived in different island environments. Each
one had a different type of beak that determined the type of food
that they could eat.
Darwin realized that there was a relationship between each
species and the food sources of the island it lived on. He was
convinced that they all shared a common ancestor. Individual
members of a species exhibit slight differences, or variations. A
variation is a slight difference in an inherited trait of individual
members of a species. For example, different humans have different
hair colors. Variations arise naturally in a population as a result of
sexual reproduction and the mutations of genes. This was the key to
Darwin’s argument. If a variation made an organism better adapted
to its environment, then it would survive to pass on its traits. If the
variation hindered the organism, then it would die before that trait
could be passed on. This idea led to Darwin’s theory of evolution by
natural selection.
Darwin realized that there was a relationship between each
species and the food sources of the island it lived on. He was
convinced that they all shared a common ancestor. Individual
members of a species exhibit slight differences, or variations. A
variation is a slight difference in an inherited trait of individual
members of a species. For example, different humans have different
hair colors. Variations arise naturally in a population as a result of
sexual reproduction and the mutations of genes. This was the key to
Darwin’s argument. If a variation made an organism better adapted
to its environment, then it would survive to pass on its traits. If the
variation hindered the organism, then it would die before that trait
could be passed on. This idea led to Darwin’s theory of evolution by
natural selection.